1. Field of the Invention
The present invention is directed to a printer or copier device system for performance-adapted production of a predetermined sheet sequence of monochromatically and/or chromatically printed single sheets, and is also directed to a printing method for producing a monochrome and chromatic sheet sequence.
2. Description of the Related Art
There is the problem in electrophotographic color printers having high print quality as known, for example, from European Patent Document EP-A1-0 629 931 that the same time is always required for producing a printed sheet both in monochrome printing mode as well as in chromatic printing mode. This means that what is referred to as the performance, i.e. the speed efficiency of the printer, is based on the full-color printing. When such a printer is utilized in mixed mode, then it is too slow for the usually occurring monochrome printing.
In electrophotographic high-performance printing with 70 pages per minute or more, the print jobs to be processed contain a majority of monochrome printouts. Only a small part of the print job is chromatic. For example, it can thus occur that a multitude of black-and-white successive sheets are printed within a print job and that one full-color image must be printed out then, for example when producing a brochure. When the usual color printing devices are utilized when producing such a brochure, these are relatively slow since, as already stated, the printing performance is based on the color printing performance. Such color printer devices are also complicated and cost-intensive and inefficiently utilized for mixed mode.
Color printer devices with which single-color or two-color printing can be carried out at high speed are disclosed, for example, by U.S. Pat. No. 5,526,107. In the known color printing means, continuous form paper is supplied to a transfer printing location of a photoconductor cylinder that respectively comprises electrophotographic units on two surfaces for producing multi-colored toner images. The continuous form paper is printed on the front side with a first color at the transfer printing location; the continuous form paper is subsequently redirected and supplied to a printing location at the same photoconductor cylinder that lies opposite the transfer printing location and the backside is printed thereat.
U.S. Pat. No. 5,596,416 discloses a printer device wherein a plurality of identical color printer means are arranged. Each of the color printer means is suited for monochromatic and color printing, whereby a parallel processing of images to be printed is possible.
What all of the known color printer devices have in common is that their performance is based on the color printing and, therefore, that the printer devices are uneconomically utilized for the mixed mode.